Researchers: Pneumonia vaccine could use improvement

Pneumonia is a leading cause of respiratory death globally, despite the fact that many children and adults are vaccinated against the disease.

A new study out of the United Kingdom, however, reveals that current vaccines may weaken infection or reduce secondary maladies but not necessarily prevent infection with the bacteria that causes pneumonia.

In a study published in Current Opinion in Pulmonary Medicine, titled “Adult pneumococcal vaccination: advances, impact, and unmet needs,” researchers identify the shortcomings of the vaccine and possible methods to increase immunity.

Jeremy S. Brown, PhD, a professor in the Center of Inflammation and Tissue Repair at University College London Respiratory and co-author of the study, said while the report isn’t going as far as to say existing versions of the pneumonia vaccine have poor efficacy, they may prevent some complications of the disease better than the disease itself.
“The ‘old’ adult vaccine PPV is not effective at preventing pneumonia in adults; but does seem to prevent S. pneumoniae septicaemia, which in adults is usually a complication of pneumonia and makes the disease more severe,” Brown told Medical Economics. “So it’s probably still useful and beneficial but according to the U.K. vaccine committee the cost benefit analysis is marginal.”

Using the PCV vaccine in children is very effective against vaccine serotypes for preventing septicemia and meningitis, as well as pneumonia, Brown said, while the PPV vaccine for adults prevent septicemia but not pneumonia itself.

Next: Treating adults with PCV

Treating adults with PCV

It may seem obvious then to vaccinate adults with the PCV vaccine as well, particularly since seniors have a reduced response to the PPV vaccine and increased survival with PCV over the PPV vaccine in one trial. However, the study notes that PCV vaccination is expensive and its efficacy may be undermined by the reduction in the prevalence of vaccine serotypes resulting from PCV vaccination of infants.

Nations considering a move to PCV vaccination of adults must carefully weigh if the change is cost-effective-a conclusion Dutch and Japanese studies have agreed on but the U.K. has not, according to Brown.

“Vaccinating with the new conjugated vaccine prevents a proportion of adult cases of S. pneumoniae pneumonia due to the vaccine serotypes and this is why it has been recommended for use in adults in the U.S.,” Brown says. “However, again the U.K. feels that this is not cost effective, as the proportion of cases of adult pneumonia caused by vaccine types is low and falling as a result of herd immunity generated by vaccinating children with same PCV vaccine.”

U.K. studies have determined that a move from PPV to PCV vaccination for adults would not be cost-effective considering the herd immunity seen with infant immunization, and that PCV vaccination should be reserved only for the immunocompromised or possibly with certain respiratory comorbidities.

Making the change to the PCV vaccine could become more cost effective if the vaccine could prevent 25% of COPD exacerbations or if an adult-specific version of PCV was created, according to the report, but further investigation would be required.

Until then, the Brown recommends physicians continue with their country’s own recommendation on which vaccine to use.

“But realize this is not a panacea and won’t prevent most cases of S. pneumoniae pneumonia and that better vaccines are needed,” Brown said. “We still want clinicians to keep following their country’s vaccination policy and we would like to see the uptake of the existing vaccines in the risk groups improve, despite the article highlighting that the existing vaccines are not yet perfect.”